Medical robotic system adapted to inhibit motions resulting in excessive end effector forces

Abstract

A medical robotic system includes a surgical instrument, a robotic arm assembly, an input device, and a processor. The surgical instrument has an end effector and a sensor for sensing a force exerted by the end effector, and is operatively mounted on the robotic arm assembly. The processor is configured to receive commanded movement of the end effector from the input device, receive information of the force from the sensor, determine a reduced velocity of the commanded movement that would inhibit damage causing motion of the end effector, and control robotic manipulation of the surgical instrument in response to the commanded movement of the end effector while restricting the velocity of the commanded movement to the reduced velocity.

1. A system comprising:
 a robotic surgical instrument having an end effector; 
 an input device that generates commanded movement of the end effector; and 
 a master/slave control system coupled to the input device and to the end effector,
 wherein the master/slave control system receives the commanded movement of the end effector, and 
 wherein in response to the commanded movement of the end effector, the master/slave control system restricts a velocity of the commanded movement to a determined reduced velocity if the velocity of the commanded movement would cause a suture held by the end effector to break. 
 
 
     
     
       2. The system of  claim 1 , wherein the master/slave control system further comprises:
 a warning system, wherein the warning system generates a warning if the velocity of the commanded movement would cause the suture held by the end effector to break. 
 
     
     
       3. The system of  claim 2 , wherein the warning includes visual information. 
     
     
       4. The system of  claim 2 , wherein the warning includes non-visual information. 
     
     
       5. The system of  claim 4 , wherein the non-visual information includes at least one of tactile sense information and sound information. 
     
     
       6. The system of  claim 1 , wherein the master/slave control system further comprises:
 a simulated slave processing unit,
 wherein the simulated slave processing unit receives a desired Cartesian velocity signal and a desired Cartesian position signal that are based on the commanded movement of the end effector, and 
 wherein the simulated slave processing unit generates a physical slave joint velocity command and a physical slave joint position command so that the velocity of the commanded movement is limited to the determined reduced velocity if the velocity of the commanded movement would cause the suture held by the end effector to break. 
 
 
     
     
       7. The system of  claim 6 , wherein the simulated slave processing unit further comprises:
 a Cartesian velocity limiter coupled to receive a Cartesian force signal,
 wherein the Cartesian force signal represents a force exerted by the end effector, and 
 wherein the Cartesian velocity limiter generates a limited Cartesian reference velocity signal that limits a component of the desired Cartesian velocity in a direction of the Cartesian force; and 
 
 a simulator coupled to the Cartesian velocity limiter to receive the limited Cartesian reference velocity signal,
 wherein the simulator generates a simulated joint velocity and a simulated joint position, and 
 wherein the simulator limits the simulated joint velocity to a determined reduced velocity if the velocity of the commanded movement would cause the suture held by the end effector to break. 
 
 
     
     
       8. The system of  claim 7 , wherein the simulated slave processing unit further comprises:
 a post-processor coupled to receive the simulated joint velocity and the simulated joint position from the simulator,
 wherein the post-processor filters the simulated joint velocity and the simulated joint position, and 
 wherein the post-processor generates the physical slave joint velocity command and the physical slave joint position command. 
 
 
     
     
       9. The system of  claim 6 , wherein the simulated slave processing unit further comprises:
 a simulator coupled to receive the desired Cartesian reference velocity signal and coupled to receive a Cartesian force signal,
 wherein the Cartesian force signal represents a force exerted by the end effector, 
 wherein the simulator generates a simulated joint velocity and a simulated joint position, and 
 wherein the simulator limits the simulated joint velocity to a determined reduced velocity if the velocity of the commanded movement would cause the suture held by the end effector to break. 
 
 
     
     
       10. The system of  claim 9 , wherein the simulated slave processing unit further comprises:
 a post-processor coupled to receive the simulated joint velocity and the simulated joint position from the simulator,
 wherein the post-processor filters the simulated joint velocity and the simulated joint position from the simulator, and 
 wherein the post-processor generates the physical slave joint velocity command and the physical slave joint position command. 
 
 
     
     
       11. The system of  claim 9 , wherein the simulator further comprises:
 a modified Jacobian inverse controller coupled to receive the desired Cartesian reference velocity signal,
 wherein the modified Jacobian inverse controller imposes limitations on the desired Cartesian reference velocity during conversion into a corresponding joint space velocity to make allowance for singularities, and 
 wherein the modified Jacobian inverse controller generates a resultant joint velocity; and 
 
 a velocity limit generator coupled to receive the Cartesian force signal,
 wherein the velocity limit generator generates a joint velocity lower limit and a joint velocity upper limit. 
 
 
     
     
       12. The system of  claim 11  wherein the simulator further comprises:
 a joint position and velocity limiter coupled to receive the resultant joint velocity from the modified Jacobian controller and coupled to receive the joint velocity lower and upper limits from the velocity limit generator,
 wherein the joint position and velocity limiter generates the simulated joint velocity and the simulated joint position. 
 
 
     
     
       13. A method comprising:
 receiving, from an input device, commanded movement of an end effector of a robotically manipulated surgical instrument; and 
 controlling robotic manipulation of the surgical instrument, in response to the commanded movement of the end effector, to restrict a velocity of the commanded movement to a determined reduced velocity if the velocity of the commanded movement would cause a suture held by the end effector to break. 
 
     
     
       14. A method comprising:
 receiving, from an input device, commanded movement of an end effector of a robotically manipulated surgical instrument; 
 controlling robotic manipulation of the surgical instrument, in response to the commanded movement of the end effector, to restrict a velocity of the commanded movement to a determined reduced velocity if the velocity of the commanded movement would cause a suture held by the end effector to break; and 
 outputting an indication of a force created by the commanded movement if the velocity of the commanded movement would cause the suture held by the end effector to break. 
 
     
     
       15. The method of  claim 14 , wherein the outputting includes outputting visual information. 
     
     
       16. The method of  claim 14 , wherein the outputting includes outputting non-visual information. 
     
     
       17. The method of  claim 16 , wherein the non-visual information includes at least one of tactile sense information and sound information. 
     
     
       18. The method of  claim 14 , wherein the outputting further comprises:
 displaying a representation of the force on a display device.